Conventionally, there is known a current detection circuit that detects an input signal current. The current detection circuit uses, for example, a method of detecting a signal current by comparing an input signal generated from the signal current with a predetermined reference signal. The reference signal is normally set according to the direct-current component of the signal current. However, when the signal current is input on an irregular basis, the direct-current component of the signal current changes according to the frequency of input. Thus, it is difficult to accurately detect a signal current even if an input signal is compared with a predetermined reference signal.
To solve such a problem, there is proposed a method of detecting a signal current by comparing a reference signal with an input signal to which the signal current is converted with the direct-current component of the signal current removed. However, the method requires a plurality of amplifier circuits, which may cause an increase in the power consumption of the current detection circuit.